Why do viruses attack other cells? They are not
alive, so how do they know what they want to do?

Question Date: 2005-10-24

Answer 1:

That is an interesting question! Philosophers
have wondered for a long time what it means to be
alive, and to be conscious or sentient. Although
of course nobody can know what it might be like to
be a virus, we can certainly gain strong clues to
the answer through the things we know from
science, philosophy, technology, and personal
experience.

In biology we dein order to be considered alive
an organism must be able to survive, adapt and
respond to its environment, and reproduce on its
own. By this definition a virus is
probably not
alive, since it really doesn't have the ability to
perform important biological processes such as
reproduction without taking over another cell.

However, this definition of living is not always
satisfactory in a non-scientific sense. Many
philosophers may argue that this is not a good
definition, because just because something needs
help from something else doesn't necessarily mean
its not alive-- after all, don't we all need help
of some sort to survive? So, to a philosopher
being considered alive may be more a question of
consciousness than of biological processes.

For example, people used to think of animals as
automatons. According to the scientific
definition, animals were certainly alive.
However, people doubted that they had any
consciousness. They thought that animals didn't
really think or feel emotions, they just responded
to things based on instincts. Because of this,
animals didn't have any rights and a lot of people
didn't care what happened to them at all. Of
course, if you have any pets I think from your own
personal experience you would disagree with this!

Science, philosophy, and personal experience have
all now come to the conclusion that, while an
animal is not as smart or emotionally complex as a
human, certainly animals do learn, make choices,
and experience pain and suffering and all forms of
emotion. The fact that people didn't acknowledge
this earlier was more because of prejudice and a
lack of understanding about what it means to be an
animal.

This raises a question: What other
organisms might experience things that we just
don't recognize? Do plants experience some form
of consciousness that we don't understand? What
about bacteria? And, like your question,
what about even things that may not really be
alive, like viruses?

So far, the answer to these questions is a
strong no. All of our evidence suggests that in
order to have any form of consciousness at all an
organism must have certain organized biological
structures that all of these organisms lack. In
the case of a virus, its particularly clear,
because a virus really lacks any form of
independence whatsoever. So, the answer to your
question is that, because a virus has no
consciousness, it actually does not make choices,
or have knowledge, or goals-- it actually does
not know what it wants to do!

So, if a virus can't know what it wants to do,
how does it do things? Think about all of
the technological devices you have in your home
and school, and how they work on their own. Your
alarm clock keeps the time, and makes a noise to
wake you up at just the right time. Your
refrigerator or home air conditioner turns itself
on or off to maintain just the right temperature.
Your answering machine can tell when somebody
calls, and then answers the phone and records a
message. If you were an alien who saw these
things for the first time you might think these
were the living creatures that inhabit the earth!
Butdo any of these devices do what they do
because they want to? You will say of course
not, they are just following a program, doing what
they were built to do.

Viruses are very similar! They are relatively
simple biological devices that just simply follow
a program, doing what they are built to do, though
instead of being electronic or mechanical they are
genetic in nature! Actually, this is why we also
use the word virus to explain small sneaky
computer programs that spread over the internet
and cause problems. Computer viruses aren't alive
or conscious either, but they certainly behave
just like biological viruses, spreading from one
computer to another and causing damage!

Did you know that your body is full of even
more complicated cells that behave by just
following programs? Every day you do things
that are the result of conscious choices: you eat
something for breakfast, you go to school, you
talk to your friends, you do your homework (of
course), you read a book. However, your body is
doing millions of things you aren't even aware of!
Your heart is beating, your lungs are breathing,
your muscles are contracting and relaxing, your
immune system is fighting infections, your
digestive system is extracting nutrients from
food, etc. All of the cells involved in those
processes are just doing what they are genetically
programmed to do, without any thought whatsoever.